#include <iostream>
using namespace std;

int main()
{
	double s;	cin >> s;

	double sum = 0.0, tmp = 2.0;
	int cnt = 0; // 存储步数

	while (sum <= s)
	{
		sum += tmp;
		tmp = tmp * 0.98;
		cnt++;
	}

	cout << cnt << endl;

	return 0;
}